1. Field of the Invention
The present invention relates to a received voice playback apparatus.
2. Description of the Related Art
Conventionally, there is a technology applied to a communications terminal for converting a received voice signal into a voice (sound) that can be clearly heard by the operator, and outputting the converted voice. For example, Japanese Patent No. 3286924 (Patent Document 1) discloses a technology applied to a mobile communications terminal provided with a function of adjusting frequency sensitivity characteristics of received vocal signals. According to patent document 1, a digital filter is used for adjusting frequency sensitivity characteristics. Plural types of tap coefficients, which are used for setting characteristics of the digital filter, are provided beforehand. Accordingly, even if the mobile communications terminal is used outdoors where the ambient noise is high, or even if the mobile communications terminal is used by an elderly person who has difficulty in hearing, it will be possible to make adjustments in such a manner that the original voice of the received signal is reproduced to be a clear, easy-to-hear voice.
Patent Document 1: Japanese Patent No. 3286924
However, the technology applied to the mobile communications terminal disclosed in Patent Document 1 involves the process of setting in advance the coefficient values that are multiplied by each frequency. Therefore, if an inappropriate coefficient value is set for the received voice signal, there will be cases where the output voice is hard to hear by the operator of the mobile communications terminal.
For example, in a case where an output value corresponding to a high frequency of a received voice signal is large, if a coefficient has been set such that the high frequency of the received voice signal is to be emphasized, the output voice will be hard to hear.